The present invention relates to a method and an apparatus for determining the distance of a light beam from a point on a surface of an object by means of a light sensor with a planar measuring field.
Such methods and apparatuses are employed in particular when orienting objects relative to one another. It is thus known, e.g., for cylindrical bearing surfaces of two turbine rotor bearings spaced at a distance to one another and use of a light beam together with a light sensor to be arranged such that the center lines or axial centers of the curves are aligned among each other respectively with each other. To this end, the axial center of the curve of the bearing surface of one of the two turbine rotor bearings is made to coincide with the light beam, which is generally a laser beam. The distances of selected points on the bearing surface of the other turbine rotor bearing from the laser beam—serving here as a reference axis—are then determined by shining the laser beam at the planar measuring field of the sensor such that the distances can be calculated on the basis of the captured positions of the point of light on the measuring field. In turn, the distances so obtained can be used to determine the position into which the second turbine rotor bearing must be brought in order for the center lines or axial centers of the curves of the bearing surfaces to align with one another.
Methods and apparatuses for determining the distance of points or surfaces of an object from a light beam are known e.g. from U.S. Pat. No. 5,717,491, U.S. Pat. No. 5,576,826, U.S. Pat. No. 7,403,294 B2, U.S. Pat. No. 7,486,390 B2, U.S. Pat. No. 8,037,615, DE 10 2004 020 406 A1, EP 0 543 971 B1, JP10213416 A and US 2005/0068521 A1. A measuring apparatus having a measuring probe for measuring an object surface is known from DE 20 2004 002 121 U1.
In the method for orientation of objects described above, the measuring field is arranged perpendicular or nearly perpendicular to the light beam in order to obtain the most accurate distance measurement possible, as the measuring field functions with the greatest accuracy in this position. The perpendicular orientation of the measuring field is usually effected using additional measuring devices, such as an additional measuring field or a position detector; in the event that multiple points on the surface of the object are to be measured, the positioning of the measuring field must often be repeated multiple times. In the solutions in the prior art, then, the perpendicular orientation of the measuring field is associated with significant effort and difficulty, which in turn increases the difficulty and time required to determine or measure the distance.